1. Technical Field
The present invention relates to a voltage regulator. More specifically, the present invention relate to a voltage regulator and an apparatus for controlling a bias current according to an output voltage.
2. Related Art
As mobile information devices, such as a smartphone, a tablet PC, etc., which use semiconductor memory devices as storage media, become more widely used, interest in and importance of semiconductor memory devices are significantly increasing. Thus, with the advent of various applications in addition to parallelization with high-speed processors or a multi-core, higher performance and reliability are required of semiconductor memory devices.
Semiconductor memory devices are storage devices implemented with semiconductors such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), and indium phosphide (InP). Semiconductor memory devices are largely divided into volatile memory devices and nonvolatile memory devices. Volatile memory devices lose stored data when power supply is interrupted. Examples of volatile memory devices include a static RAM (SRAM), a dynamic RAM (DRAM), and a synchronous DRAM (SDRAM). Non-volatile memory devices maintain stored data even when power supply is interrupted. Examples of non-volatile memory devices include a read only memory (ROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a flash memory, a phase change RAM (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), a ferroelectric RAM (FRAM), and so on. Flash memories are generally divided into a NOR type and a NAND type.
Semiconductor memory devices include several functional blocks. A constant voltage generation device may be used to supply power to each functional block. A voltage regulator is configured to convert an external power voltage into a stable power voltage to stably supply the power voltage to the several functional blocks, that is, driving circuits.